A novel electrolysis cell has been developed for CO 2 reduction to CO in an ionic liquid/organic solvent electrolyte. The electrolysis cell is separated into two compartments by an ion-exchange membrane (Nafion117). The cathode compartment is filled with a CO 2 saturated 1-butyl-3-methyl-imidazolium trifluoromethanesulfonates ([Bmim][CF 3 SO 3 ])/propylene carbonate (PC) solution. The anode compartment is filled with a 0.1 M H 2 SO 4 aqueous solution. A Ag foil and a graphite rod are used as the cathode and the anode respectively. In this electrolysis cell, CO 2 reduction can be carried out in the nonaqueous electrolyte, and H 2 O oxidation can be carried out in the aqueous solution. Thus CO can be produced from CO 2 and H 2 O. Owing to the high solubility of CO 2 in the nonaqueous electrolyte, the Faradaic efficiency of CO formation is high, reached 90.1% at −1.72 V (vs Pt wire). After 3 h electrolysis, no poisonous species are observed on the cathode. The Ag electrode exhibits a high electrocatalytic activity for CO 2 reduction to CO.